\input pstfig
$
\setcoorunit{4}{1}
\psset{xunit=0.4\psyunit}
%\drawaxes{-2.6}{5}{-3}{3.2}
\drawaxes{-3.5}{4}{-2.2}{2.3}
\markxlabel{0}{\scriptstyle O}{1em}
\uput[45](0,1){\pi}
\uput[-171](0, 0.5){\nfrac{\pi}{2}}
\uput[-9](0,-0.5){\!-\nfrac{\pi}{2}}
\uput[-45](0,-1){-\pi}
%\psset{showpoints=true}
\psplot{ 1}{ 3}{asin(1/x)/\pinum   }
\psplot{-3}{-1}{-asin(1/x)/\pinum-1}
\thinline
\psplot{ 1}{ 3}{asin(1/x)/\pinum   -2}
\psplot{ 1}{ 3}{-asin(1/x)/\pinum  -1}
\psplot{ 1}{ 3}{-asin(1/x)/\pinum  +1}
\psplot{-3}{-1}{-asin(1/x)/\pinum-1+2}
\psplot{-3}{-1}{asin(1/x)/\pinum   +2}
\psplot{-3}{-1}{asin(1/x)/\pinum     }
\dashline
\psline(-3, 1)(3, 1)
\psline(-3, 2)(3, 2)
\psline(-3,-1)(3,-1)
\psline(-3,-2)(3,-2)
\psline(-1,-0.5)(0,-0.5)
\psline( 0, 0.5)(1,0.5)
$
\bye
